quinta-feira, 27 de agosto de 2015

Global sea levels climbed 3 inches since 1992, NASA research shows

Sea levels
worldwide rose an average of nearly 3 inches (8 cm) since 1992, the
result of warming waters and melting ice, a panel of NASA scientists
said on Wednesday.In
2013, a United Nations panel predicted sea levels would rise from 1 to 3
feet (0.3 to 0.9 meters) by the end of the century. The new research
shows that sea level rise most likely will be at the high end of that
range, said University of Colorado geophysicist Steve Nerem.Sea levels are rising faster than they did 50 years ago and “it’s very likely to get worse in the future,” Nerem said. The
changes are not uniform. Some areas showed sea levels rising more than 9
inches (25 cm) and other regions, such as along the U.S. West Coast,
actually falling, according to an analysis of 23 years of satellite
data.Scientists believe
ocean currents and natural cycles are temporarily offsetting a sea level
rise in the Pacific and the U.S. West Coast could see a significant
hike in sea levels in the next 20 years.“People
need to understand that the planet is not only changing, it’s changed,”
NASA scientist Tom Wagner told reporters on a conference call.“If
you’re going to put in major infrastructure like a water treatment
plant or a power plant in a coastal zone ... we have data you can now
use to estimate what the impacts are going to be in the next 100 years,”
Wagner said.Low-lying
regions, such as Florida, are especially vulnerable, added Michael
Freilich, director of NASA's Earth Science Division.”Even
today, normal spring high tides cause street flooding in sections of
Miami, something that didn’t happen regularly just a few decades ago,”
Feilich said.More than 150 million people, mostly in Asia, live within 3 feet (1 meter) of the sea, he added.The
biggest uncertainty in forecasting sea level rise is determining how
quickly the polar ice sheets will melt in response to warming
temperatures.“Significant
changes are taking place today on ice sheets,” said Eric Rignot, a
glaciologist at the University of California in Irvine. “It would take
centuries to reverse the trend of ice retreat.”Scientists
said about one-third of the rise in sea levels is due to the expansion
of warmer ocean water, one-third to ice loss from the polar ice sheets
and the remaining third to melting mountain glaciers.